This table is a Summary of SIP Timers that are refined in RFC 3261.
Timer | Default value | Section | Meaning |
|---|---|---|---|
T1 | 500 ms | 17.1.1.1 | Round-trip time (RTT) estimate |
T2 | 4 sec | 17.1.1.2 | Maximum retransmission interval for non-INVITE requests and INVITE responses |
T4 | 5 sec | 17.1.1.2 | Maximum duration that a message can remain in the network |
Timer A | initially T1 | 17.1.1.2 | INVITE request retransmission interval, for UDP only |
Timer B | 64*T1 | 17.1.1.2 | INVITE transaction timeout timer |
Timer D | >32 sec for UDP 0 sec for TCP/TLS | 17.1.1.2 | Wait time for response retransmissions |
Timer E | initially T1 | 17.1.1.2 | Non-INVITE request retransmission interval, UDP only |
Timer F | 64*T1 | 17.1.1.2 | Non-INVITE transaction timeout timer |
Timer G | initially T1 | 17.2.1 | INVITE response retransmission interval |
Timer H | 64*T1 | 17.2.1 | Wait time for ACK receipt |
Timer I | T4 for UDP 0 sec for TCP/TLS | 17.2.1 | Wait time for ACK retransmissions |
Timer J | 64*T1 for UDP 0 sec | 17.2.2 | Wait time for retransmissions of non-INVITE requests |
Timer K | T4 for UDP 0 sec for TCP/TLS | 17.2.2.1 | Wait time for response retransmissions |